113 results about "Density functional theory" patented technology

The invention refers to a method for the accurate determination of van der Waals parameters for high-precision determination of crystal structures and/or energies, comprising the steps of: numerically simulating at least one crystal structure based on density functional theory (DFT) calculations combined with a potential energy term representing van der Waals interactions; providing reference data containing accurate information about said at least one crystal structure; defining a deviation function (F) quantifying a deviation between said reference data and said at least one simulated crystal structure; fitting at least one parameter of said van der Waals potential term in such a way as to minimize said deviation function (F); and obtaining the accurate van der Waals parameters from the best fit. The invention furthermore deals with a hybrid method for the accurate van der Waals parameters from the best fit. The invention furthermore deals with a hybrid method for the accurate determination of crystal structures and/or energies based on such a parameter determination as well as the general application of such a hybrid method to the energy ranking of polymorphic crystal structures.

Methods, systems, and computer program products for computational polymer processing including, without limitation, computational amphiphilic polymer design, conformational energy minimization, generation and refinement of torsional parameters for sub-units of potential polymers, generation of modified force field parameters, and prediction of conformational information for potential polymers. A target polymer backbone or portion thereof is identified. Small model compounds that have structural connectivities that are similar to structural connectivities of the target polymer backbone or portion thereof, are identified, whereby the combination of the small model compounds serve as a model of the target polymer or portion thereof. Gradient-corrected density functional theory (“DFT”) torsional potentials are calculated for the small model compounds, wherein energies are calculated at unconstrained and constrained geometries of the selected small model compounds. New torsional parameters are then obtained from the DFT torsional potentials. The new torsional parameters are combined with other terms to form a modified (or new) force field for the target polymer backbone or portion thereof. Molecular dynamics and configurational-biased Monte Carlo (“MD/MC”) simulations are performed using the modified force field, whereby results of the MD/MC simulations serve as predicted conformation properties of the target polymer backbone. The predicted conformation properties for the multiple target polymer backbones are then used to select one or more of the target polymer backbones as candidate amphiphilic polymer backbones for synthesis.

The invention discloses a method for qualitatively and quantitatively analyzing histamine in muscles of miichthys miiuy by surface-enhanced Raman spectroscopy. The method comprises the following steps: mincing the muscles of the miichthys miiuy, making the minced muscles into minced meat, weighing certain parts of equivalent miichthys miiuy muscles to serve as samples, preparing histamine standard solutions of different concentrations, adding the histamine standard solutions into the samples, and using samples at different time points as labeling samples and prediction samples in a storage process; adding the labeling samples and the prediction samples into trichloroacetic acid, and filtering to obtain an extracting solution; measuring the histamine content of the miichthys miiuy meat of the prediction samples through HPLC (High Performance Liquid Chromatography); adding a nanometer enhancer into the extracting solution of the labeling samples, performing Raman spectrum data acquisition, and calculating corresponding Raman characteristic peaks of the histamine by a density functional theory; establishing a quantitative analysis model by using the peak intensity of the Raman characteristic peaks and the histamine content, and measuring the histamine concentration of the muscles of the miichthys miiuy by the quantitative analysis model. By adopting the method, the content of histamine of which the concentration is 1 to 150 mg/L in fresh fish can be detected accurately and quickly.

The invention relates to a preparation method for a phosphorus-nitrogen doped carbon nanotube. The method comprises the following steps: 1) putting a Fe/Y catalyst and red phosphorus into a ceramic boat, heating a quartz tube type furnace to 900 to 1,100 K, introducing Ar/diethylamine mixed gas, maintaining the constant temperature for 0.5 to 1.51 hours and naturally cooling to obtain a mixture of the black phosphorus-nitrogen doped carbon nanotube and the Fe/Y catalyst, wherein the chemical formula of the phosphorus-nitrogen doped carbon nanotube is CNxPy; x is more than 0.5 and less than 1; and y is more than 0.5 and less than 1; and 2) removing a Fe/NaY molecular sieve from dilute solution of HF to obtain the phosphorus-nitrogen doped carbon nanotube. The phosphorus-nitrogen is doped, so that light transition absorption and heat conductivity coefficient of a single-wall carbon nanotube can be obviously changed. The research on the density functional theory of the phosphorus-nitrogen doped single-wall carbon nanotube shows that the phosphorus is replaced to serve as a scattering center, so that local electronic state electron can be established and the transportation characteristic of the single-wall carbon nanotube is modified. In addition, the phosphorus-nitrogen is doped, so the mechanical strength of the single-wall carbon nanotube is changed, and the breaking elongation is reduced by 50 percent.

The invention discloses a simulation method of a graphene doped structure. The method comprises the following steps of establishing an atom structure model of intrinsic graphene; doping the intrinsicgraphene; optimizing the doped graphene structure; and performing simulation calculation on the structure, the energy band, the state density and the current density of the intrinsic graphene and thedoped graphene by means of a density functional theory and plane wave pseudo-potential method. The method realizes simulation calculation on the structure, the energy band, the state density and the current density of the intrinsic graphene and the Pt/Pd atom doped graphene. The method discloses a fact that the band gap of the graphene can be opened through doping the Pt/Pd atoms into the intrinsic graphene, thereby improving conductivity of the graphene; and through increasing the content of the doping atoms Pt, the band gap of the doped structure can be increased, thereby realizing higher density of the energy band curves and increasing charge transfer degree.

A method for predicting characteristics of a compound includes collecting a first experimental information database for characteristics of reference compounds according to a quantum phenomenon, collecting a simulation database for characteristics of the reference compounds according to the quantum phenomenon by applying density functional theory methods, comparing the simulation database to the first experimental information database for each reference compound to calculate accuracy of the simulation database, clustering the reference compounds into clusters based on the accuracy of the simulation database and designating a proper density functional theory method for each cluster, comparing a similarity between a test compound to predict a characteristic according to the quantum phenomenon and the reference compounds included in each cluster, determining a proper density functional theory method for the test compound according to the similarity, and conducting a simulation with the test compound according to the determined density functional theory method.

The invention provides a method for revealing a nano bi-metal CoNi adsorption mechanism based on the density functional theory and belongs to the technical field of chemical engineering. A nano adsorbent is prepared through simple reduction reaction under the room-temperature air, and the efficient adsorption mechanism of the adsorbent is deeply analyzed by applying a computer simulation auxiliary adsorption experiment result based on the density functional theory. The method comprises the following steps that 1, CoNi bi-metal nano particles are prepared; 2, the adsorption performance of the CoNi bi-metal nano particles is tested; 3, a CoNi bi-metal surface model is constructed; and 4, the surface property of the CoNi bi-metal surface model is calculated. According to the method for revealing the nano bi-metal CoNi adsorption mechanism based on the density functional theory, the method that density functional theory calculation and the experiment result are combined is adopted to illustrate that the adsorption performance of the CoNi bi-metal nano particles is superior to that of single metal (Co or Ni) on the molecule and atom level, and the efficient adsorption mechanism of the CoNi bi-metal nano particles is revealed by analyzing the surface energy, the work function, the state density, the surface atomic charge difference density and the d belt center of the surface model.

The invention discloses a method for revealing a mechanism of influence of humidity on polluted gases in TiO2 photocatalytic degradation. A theoretical calculation and analysis method based on a density functional theory adsorption simulation and catalytic reaction mechanism is used to assist a photocatalytic degradation experiment, and study the mechanism of affecting the TiO2 photocatalytic degradation gaseous pollutants by the humidity. The method comprises the following steps of studying an influence experiment of the humidity on TiO2 photocatalytic degradation gaseous pollutants; simulating the adsorption process of the gaseous pollutants on the surface of the TiO2 under the action of different water molecules; and analyzing the photocatalytic reaction mechanism of generating hydroxylradical oxidized gaseous pollutants by H2O molecules. According to the method of the invention, a photocatalysis experiment is combined with simulation calculation and theoretical analysis, in combination with a photocatalytic degradation experiment, the influence mechanism of the humidity on the TiO2 photocatalytic degradation gaseous pollutants is disclosed from multiple perspectives from the perspective of adsorption and catalytic reaction, and a theoretical foundation is laid for the practical application of a photocatalytic oxidation technology.

Provided is an electromagnetic wave absorber, including a base material and a porous carbon material containing, as a raw material, a plant-based material having a silicon content of 5% by mass or more, in which the porous carbon material has a specific surface area value as measured by the nitrogen BET method of 400 m2/g or more, a silicon content of 1% by mass or less, a pore volume as measured by the BJH method of 0.2 cm3/g or more, and a pore volume as measured by the MP method of 0.2 cm3/g or more, or a total pore volume of pores each having a diameter in the range from 110-9 m to 510-7 m as measured by the Non Localized Density Functional Theory of 1.0 cm3/g or more.

The invention relates to high-capacity long-service-life AB<4.5> type hydrogen storage alloy and a preparation method thereof. By adjusting and controlling the stoichiometric ratio and the Mg contentof AB<5> type hydrogen storage alloy, the effect that Mg accurately replaces Ni atoms in the alloy is achieved. Through a density functional theory method, that is, the DFT method, the rationality ofalloy design is verified. According to the high-capacity long-service-life AB4.5 type hydrogen storage alloy and the preparation method thereof, under guidance of the density functional theory, the high-capacity long-service-life AB4.5 type hydrogen storage alloy is designed and prepared, the capacity of the prepared alloy reaches 326.7 mAh g<-1>, and the cycle life is 928 frequencies and is almost two times that of traditional commercial hydrogen storage alloy; the cost reduction purpose is achieved by prolonging the cyclic life of the hydrogen storage alloy, meanwhile, the capacity of the alloy is improved, and the effect that the alloy is applied to nickel-metal hydride batteries is hopefully achieved.

The particle of the present invention is a high-density particle to which a target substance can be bound, wherein the surface of the particle body is a roughened surface. The particle is characterized in that a substance or functional group to which a target substance can bind is immobilized on the roughened surface of the particle body, and the specific surface area of the particle is 1.4 to 100 times the specific surface area of a true spherical particle having the same particle size and the same density as those of the particle of the invention. In the particle of the invention, the accumulated micropore volume [cm³] of micropores having radius of not less than 20 nm per unit surface area [cm²] is not less than 1×10⁻⁶ [cm³/cm²].

The invention discloses a confirmation method for efficiently and harmlessly degrading SF6 waste gas through dielectric barrier discharge. The method comprises the following steps: building an experimental platform; acquiring discharge parameters and experiment parameters of SF6 degradation by using a DBD reactor of the experiment platform; carrying out gas distribution on background gas and SF6 gas; by adopting a control variable method, promoting SF6 forward decomposition experiment research to obtain optimal condition for decomposing SF6 ; analyzing the chemical reaction mechanism of the SF6 gas under discharge degradation by combining a density functional theory and chemical reaction kinetics; and establishing a physical model for degrading SF6 through dielectric barrier discharge according to various basic physical coefficients of the physical model. According to the invention, the SF6 gas is fully degraded through a dielectric barrier discharge SF6 degradation system, and products obtained after SF6 degradation are comprehensively detected and analyzed through an analysis and detection system, so that optimal degradation parameter configuration and degradation equipment configuration are obtained, the configuration is more scientific, and the degradation energy efficiency is higher.

The invention discloses an identification method of a eutectic structure of explosive. The identification method comprises the following steps: firstly determining Raman spectra of a eutectic explosive sample and single-substance explosive samples to obtain corresponding fingerprint spectrum characteristic peaks; adopting a B3LYP mixing functional method, and calculating vibration frequencies of explosive molecules respectively by using a DFT (Density Functional Theory); then identifying the fingerprint spectrum characteristic peaks of the explosive molecules and attributing a vibration mode; and finally, comparing the Raman spectra of the eutectic explosive sample and the two single-substance explosive samples, attributing the vibration mode of the eutectic explosive sample according to vibration peak displacement of the fingerprint spectrum characteristic peaks of the two single-substance explosive samples, and analyzing the forming reasons of the eutectic structure through Raman characteristic displacement. According to the identification method, the eutectic structure of the explosive is rapidly analyzed and identified by simply mixing the single-substance explosive and the single-substance explosive mixed two by two, and taking the single-substance explosive to react two by two to form the inconsistent eutectic Raman spectra and generate different Raman peak position changes.

The invention discloses an efficient electron carrier screening, designing and modifying method, and belongs to the field of bioelectrochemical catalysis. According to the invention, Shewanella oneidensis is used as an experimental object to screen and modify an electron carrier so as to improve the extracellular electron transfer capability of the electron carrier. In order to screen out electroncarriers with excellent performance, a single-chamber bioelectrochemical system and a double-chamber bioelectrochemical system are established, a microbial extracellular electron transfer detection method is established and perfected, and evaluation indexes such as cytotoxicity, current density, reduction equivalent and coulombic efficiency are determined. In order to further improve the performance of the electron carrier, the anthraquinone-2-sodium sulfonate (AQS) electron carrier is reasonably designed and modified based on a density functional theory, and seven substituent group positionsand six side chain groups are selected for theoretical calculation of standard Gibbs free energy change and oxidation-reduction potential. Experimental analysis proves that the method for reducing the redox potential of the electron carrier through design and transformation is an effective method for improving the extracellular electron transfer capacity of electroactive microorganisms.

The invention discloses a high-density functional knitted fabric and use thereof. The knitted fabric is formed by a cotton yarn of 50-80 English count and a composite yarn containing a modified cross-cection polyester filament with a fineness of 50-80 English count, wherein the content of the cotton yarn is, by weight, 20-55%. The use of the high-count cotton yarn gives the fabric delicate hand feeling and good moisture absorption properties, meanwhile the fine-size composite yarn containing the modified cross-cection polyester filament gives the fabric a good moisture absorption and quick-drying property, the wearing comfort is improved, and the fabric can be used for producing functional upper garment and lower garments.

The invention discloses a metal/gamma-Graphene composite model and a method for modifying electronic performance of gamma-Graphene. The method includes the steps: respectively establishing models forthe metal crystal and the gamma-Graphene by adopting quantum mechanics simulation software calculated on the basis of a first principle of a density functional theory to obtain a six-layer metal crystal surface unit cell model and a gamma-Graphene unit cell model; and selecting a metal crystal surface supercell and a gamma-Graphene supercell with the minimum mismatching ratio to construct a six-layer metal crystal surface/gamma-Graphene composite model, and optimizing the structure of the six-layer metal crystal surface/gamma-Graphene composite model to obtain a metal/gamma-Graphene compositemodel with the lowest total internal energy of atoms. According to the method for modifying electronic performance of gamma-Graphene disclosed by the invention, the damage to the lattice integrity ofgamma-Graphene is avoided; the method is low in calculation cost, simple to operate, high in accuracy, wide in application and good in repeatability; the constructed metal/gamma-Graphene composite model provides a theoretical model and explanation in principle for experimental preparation of related materials and devices.

The invention discloses a multidimensional simulating method for hydrogen retention and desorption in tungsten in a radiation environment. The method comprises the following steps of by means of a binary collision approximation method, calculating a primary off-position damage generated by irradiation and spatial distribution thereof; by means of a density functional theory method, calculating atom scale physical parameters of radiation defects and hydrogen in the tungsten, and estimating the physical parameter of a relatively large defect cluster; and by means of an object dynamics Monte-Carlo method, simulating long-time cooperative evolution of the hydrogen and the radiation defect in the radiation environment. According to the multidimensional simulating method, a DFT, a BCA and an OKMC method are combined, thereby realizing sequence multidimensional analysis of defect evolution. Compared with an existing simulating method, the multidimensional simulating method has advantages of accurately describing hydrogen-defect interaction, improving simulated time and space dimension to above hour/micrometer magnitude, and conveniently examining the influence of micro parameters such asirradiation ion energy, flux and temperature to hydrogen retention/desorption. The multidimensional simulating method is particularly suitable for long-time simulation of hydrogen retention and desorption in the tungsten in the radiation environment.

The invention provides a rapid detection method of sulfadiazine in an animal body, and a Raman characteristic peak of sulfadiazine is determined by using a density functional theory. The method comprises a step of establishing a quantitative analysis curve according to the characteristic peak intensity with high Raman peak intensity and a good peak pattern. Standard recovery experiments show thatthe method is good in accuracy and precision. The lowest concentration of sulfadiazine in the animal body detected by the method is 2 mg/L. According to the method, the sulfonamide antibiotic residuesin the swine urine are qualitatively and quantitatively analyzed, single sample detection is completed within 3 min, and a rapid and convenient detection method is provided for rapid qualitative screening and preliminary quantitative detection of the sulfonamide antibiotic residues in the swine urine.